Herbicidal 1-aryl-Δ2 -1,2,4-triazolin-5-ones

ABSTRACT

Novel aryltriazolinone compounds of the formula ##STR1## in which X is a chlorine or bromine atom and R is a radical selected from the group consisting of methyl, ethyl, 1-methylethyl, methoxymethyl, 2-methoxyethyl, 1-methyl-2-methoxyethyl, 2-propenyl, 2-propynyl, and 1-methyl-2-propynyl have herbicidal utility against a variety of grassy and broadleaf weeds in both preemergence and postemergence applications and show a selectivity favorable to cotton in preemergence applications.

This application is a continuation-in-part of U.S. application Ser. No.673,291, filed Nov. 20, 1984, now abandoned, which is acontinuation-in-part of U.S. application Ser. No. 594,602, filed Mar.29, 1984, now abandoned.

The invention described in this application pertains to weed control inagriculture, horticulture, or other fields where there is a desire tocontrol unwanted plant growth. More specifically, the presentapplication describes novel herbicidal 1-aryl-Δ²-1,2,4-triazolin-5-ones, herbicidal compositions containing the newcompounds, methods for preparing the compounds, and methods forpreventing or destroying undesired plant growth by preemergence orpostemergence application of the herbicidal compositions to the lcouswhere control is desired. The present compounds may be used toeffectively control a variety of both grassy and broadleaf plantspecies.

Various herbicidal 1-aryl-Δ² -1,2,4-triazolin-5-ones are known in theart. U.S. Pat. No. 4,318,731 and corresponding British Pat. No.2,056,971 disclose herbicidal aryltriazolinones of the formula ##STR2##wherein R¹ is alkyl, R² is hydrogen, alkyl, or alkenyl, and X ishydroxy, alkyl, alkoxy, alkoxyalkoxy, alkenyloxy, oralkyloxycarbonylalkyloxy.

British Pat. No. 2,090,250, a continuation-in-part of the above Britishpatent, adds to the above genus compounds wherein R² is alkynyl,halomethyl, or haloethyl, and X is alkoxy, alkenyloxy, alkynyloxy,alkoxyalkyl, hydroxy, halomethyloxy, or haloethyloxy.

European Patent Application Publication No. 55,105 discloses a series ofherbicidal aryltriazolinones of the formula ##STR3## wherein R is alkyl,alkenyl, or cycloalkyl, X is chlorine or bromine, and Y is hydrogen oralkoxy.

Japanese Kokai No. 81-32,468 discloses herbicidal aryltriazolinones ofthe formula ##STR4## wherein R is hydrogen, alkyl, or 2-propenyl, and R¹is methyl or alkoxy.

South African Patent Application No. 78/3182 discloses herbicidalaryltriazolinones of the formula ##STR5## wherein R_(n) is hydrogen orrepresents 1 to 4 same or different radicals selected from halogen,nitro, cyano, optionally halo-substituted alkyl, alkoxy, or alkylthio,and optionally substituted phenyl or phenoxy, and R¹ is alkyl,alkoxyalkyl, dialkoxyethyl, dialkylaminoethyl, or cycloalkyl.

U.S. Pat. No. 4,315,767 discloses herbicidal bicyclic compounds of thefollowing formula ##STR6## wherein V is hydrogen, halogen, methyl, oralkoxy, X is hydrogen, halogen, cyano, methyl, methoxy, or nitro, Y ishydrogen, halogen, or methyl, m and n are 0 to 4 (m plus n is 2 to 4), Qis oxygen or sulfur, and Z is oxygen, S(O)_(p), or NR¹ wherein p is 0-2and R¹ is alkyl, provided that when m plus n is 2 or 4 then Y and X areother than hydrogen, and when Z is S(O)_(p) then n is 1 to 4.

Additional herbicidal bicyclic compounds based on the aryltriazolinonenucleus are disclosed in U.S. Pat. No. 4,213,773 and have the followingstructural formula ##STR7## wherein V is hydrogen, halogen, hydroxy,alkyl, or --OR¹ ; R¹ is optionally substituted alkyl, cycloalkyl,cycloalkylalkyl, optionally substituted alkenyl, alkynyl, optionallysubstituted benzyl, alkylaminocarbonyl, (alkyl)(methyl ormethoxy)aminocarbonyl, acyl, alkoxycarbonyl, or --CHR⁷ R⁸ wherein R⁷ ishydrogen or alkyl and R⁸ is cyano, acetyl, hydroxycarbonyl,alkoxycarbonyl, hydroxymethyl, alkoxymethyl, alkylcarbonyloxymethyl,hydroxycarbonylethenyl, alkoxycarbonylethenyl, or a group --CO--NR¹¹ R¹²wherein R¹¹ is hydrogen, alkyl, alkenyl, or alkoxy, and R¹² is hydrogenor alkyl; X is halogen, cyano, methyl, methoxy, or nitro; Y is hydrogen,halogen, or methyl; Z is hydrogen or halogen; n is 3-5; m is 0-2; and Qis oxygen or sulfur, with certain provisos.

A class of Δ² -1,2,4-triazolin-5 ones is disclosed as fungicides in U.S.Pat. No. 4,098,896. The disclosed genus has the formula ##STR8## whereinR is alkyl, alkenyl, alkynyl, cycloalkyl, or optionally substitutedphenyl or arylalkyl, R¹ is haloalkyl or haloalkenyl, and R² isoptionally substituted alkyl, alkenyl, or alkynyl, or optionallysubstituted aryl, arylalkyl, or alkylaryl.

The compounds of this invention are1-[4-halo-2-fluoro-5-(substituted)oxyphenyl]-3-methyl-4-difluoromethyl-.DELTA.²-1,2,4-triazolin-5-ones of the formula ##STR9## wherein X is chlorine orbromine and R is alkyl, alkenyl, alkynyl, alkoxyalkyl, or alkyl-S(O)_(n)-alkyl wherein n is 0 to 2.

The present compounds are named in accordance with the numbering systemshown in formula I, for the ring atoms of the heterocycle which is thesame as the numbering system used in U.S. Pat. No. 4,318,731, supra, forsmilar compounds.

A preferred subgenus of this invention comprises the compounds offormula I in which R is selected from --CH₃, --C₂ H₅, --CH(CH₃)₂, --CH₂OCH₃, --CH₂ CH₂ OCH₃, --CH(CH₃)CH₂ OCH₃, --CH₂ CH═CH₂, --CH₂ C.tbd.CH,and --CH(CH₃)C.tbd.CH.

One aspect of the present invention pertains to the compounds of formulaI in which X is a chlorine atom. A preferred subgenus of this aspect ofthe invention comprises the compounds in which R is selected from--CH(CH₃)₂, --CH₂ OCH₃, --CH(CH₃)CH₂ OCH₃, --CH₂ CH═CH₂, --CH₂ C.tbd.CH,and --CH(CH₃)C.tbd.CH. The compounds of the subgenus, particularly whereR is --CH(CH₃)₂, --CH₂ OCH₃, --CH₂ CH═CH₂, --CH₂ C.tbd.CH, or--CH(CH₃)C.tbd.CH, show a selectivity favorable to cotton inpreemergence applications at application rates which inhibit or controlemergence or growth of a variety of weeds. Specific embodiments givinggood weed control at low preemergence application rates and showing aselectivity favorable to cotton include the species in which R isvariously --CH(CH₃)₂, --CH₂ OCH₃, and --CH₂ C.tbd.CH. R isadvantageously --CH₂ OCH₃ or --CH₂ C.tbd.CH.

The compounds of formula I in which X is a bromine atom form a second,preferred aspect of the present invention. The presence of a bromineatom at the C-4 position of the phenyl ring in formula I was found togenerally give superior cotton selectivity in preemergence applicationsat application rates at which a variety of weeds are controlled. Apreferred subgenus of this aspect of the invention comprises thecompounds in which R is selected from --CH₃, --C₂ H₅, --CH(CH₃)₂, --CH₂OCH₃, --CH₂ CH₂ OCH₃, --CH₂ C.tbd.CH, and --CH(CH₃)C.tbd.CH. In apreferred specific embodiment, R is selected from --CH₃, --CH₂ OCH₃, and--CH₂ C.tbd.CH.

The present compounds, which have a fluorine atom at the C-2 position ofthe phenyl ring, in general have herbicidal properties far superior tothose of the corresponding compounds having a chlorine atom at C-2 ofthe phenyl ring, and are highly active at low application rates againsta variety of grassy and broadleaf weed species in both preemergence andpostemergence applications.

The compounds of this invention may be prepared by methods analogous tothe methods described in the references above for similar compounds orby methods within the skill of the art. The disclosures in the abovereferences pertaining to methods of preparation are incorporated hereinby reference. A method of preparation exemplified herein is illustratedin the following chemical equations for the compound of formula I inwhich X is Cl and R is --CH₂ C.tbd.CH. ##STR10##

4-Chloro-2-fluoro-5-methoxyaniline, compound II, was prepared in fivesteps from commercially available 2-chloro-4-fluorophenol in the mannerdescribed by E. Nagano et al. in European Patent Application PublicationNo. 69,855, published Jan. 19, 1983, incorporated herein by reference.Compound II was converted to the corresponding hydrazine III bydiazotization followed by reduction of the diazonium salt with stannouschloride. Treatment of the arylhydrazine with pyruvic acid in thepresence of 10% hydrochloric acid and ethanol gave the arylhydrazone IVwhich upon treatment with diphenylphosphoryl azide afforded thearyltriazolinone V. Compound V was converted to the final product inthree steps by methods analogous to those disclosed in British Pat. No.2,090,250 for similar compounds. Alkylation of Compound V withchlorodifluoromethane produced the N-difluoromethyl derivative VI whichwas demethylated at the ether linkage upon treatment with borontribromide in methylene chloride to give the corresponding phenol VII.Alkylation of the 5-hydroxyphenyl compound with propargyl bromide in thepresence of potassium carbonate and acetone produced the presentcompound.

Preparation of the present compounds and the intermediate compoundsshown in the chemical equations above is illustrated further in thefollowing examples. All temperatures shown are in degrees Celcius, andreduced pressures for concentration of liquid were produced by a vacuumpump.

EXAMPLE 1 Preparation of Intermediates A.4-Chloro-2-fluoro-5-methoxyphenylhydrazine

A stirred solution of 48.0 g (0.27 mole) of4-chloro-2-fluoro-5-methoxyaniline in 50 mL of concentrated hydrochloricacid was cooled to -5° C., and 23.5 g (0.34 mole) of sodium nitrite in100 mL of water was added dropwise. Upon complete addition, the reactionmixture was stirred at 0° C. for one hour. A solution of 154.0 g (0.68mole) of stannous chloride in 225 mL of concentrated hydrochloric acidwas cooled to 0° C., and the cold solution prepared above was slowlyadded to it. Upon complete addition, the reaction mixture was allowed towarm to ambient temperature, then was filtered to collect a solid. Thesolid was made basic and extracted with toluene. The toluene layer wasseparated and dried over magnesium sulfate, then filtered. The filtratewas concentrated under reduced pressure to give 22.4 g of4-chloro-2-fluoro-5-methoxyphenylhdrazine as a solid.

The nmr spectrum was consistent with the proposed structure.

B. Pyruvic acid, 4-chloro-2-fluoro-5-methoxyphenylhydrazone

A stirred solution of 21.0 g (0.11 mole) of4-chloro-2-fluoro-5-methoxyphenylhydrazine and 100 mL of aqueous 10%hydrochloric acid in 100 mL of ethanol was warmed to 40° C., and asolution of 10.0 g (0.114 mole) of pyruvic acid in 20 mL of water wasadded. Upon complete addition, the reaction mixture was stirred for onehour. An additional 50 mL of water was added, and the reaction mixturewas filtered to collect a solid. The solid was air dried to give 29.0 gof pyruvic acid, 4-chloro-2-fluoro-5-methoxyphenylhydrazone; mp166°-169° C.

The nmr spectrum was consistent with the proposed structure.

C. 1-(4-Chloro-2-fluoro-5-methoxyphenyl)-3-methyl-Δ²-1,2,4-triazolin-5-one

A stirred solution of 27.0 g (0.104 mole) of pyruvic acid,4-chloro-2-fluoro-5-methoxyphenylhydrazone, 29.0 g (0.105 mole) ofdiphenylphosphoryl azide, and 11.0 g (0.108 mole) of triethylamine in500 mL of toluene was heated under reflux for four hours. The reactionmixture was cooled to ambient temperature and extracted with aqueous 10%sodium hydroxide. The aqueous layer was separated and neutralized withgaseous carbon dioxide, and a solid was collected by filtration. Thesolid was air dried to give 11.0 g of1-(4-chloro-2-fluoro-5-methoxyphenyl)-3-methyl-Δ²-1,2,4-triazolin-5-one; mp 193°-195° C.

The nmr spectrum was consistent with the proposed structure.

D.1-(4-Chloro-2-fluoro-5-methoxyphenyl)-3-methyl-4-difluoromethyl-Δ.sup.2-1,2,4-triazolin-5-one

A stirred mixture of 10.0 g (0.039 mole) of1-(4-chloro-2-fluoro-5-methoxyphenyl)-3-methyl-Δ²-1,2,4-triazolin-5-one, 10.0 g (0.031 mole) of tetrabutylammoniumbromide, and 10.0 g (0.25 mole) of sodium hydroxide in 250 mL ofcyclohexane was warmed to 60° C., and 10.0 g (0.116 mole) ofchlorodifluoromethane was bubbled into the reaction mixture. Uponcomplete addition, the reaction mixture was warmed to reflux temperatureand stirred for one hour. The hot solution was decanted from a potresidue and was allowed to cool to ambient temperature. Methylenechloride was added to the cooled mixture to dissolve a solidprecipitate, and the whole was washed with aqueous 10% hydrochloricacid, then with aqueous 10% sodium hydroxide. The organic layer wasseparated and dried over magnesium sulfate, then filtered. The filtratewas concentrated under reduced pressure to give 5.0 g of1-(4-chloro-2-fluoro-5-methoxyphenyl)-3-methyl-4-difluoromethyl-Δ.sup.2-1,2,4-triazolin-5-one; mp 86°-88° C.

The nmr spectrum was consistent with the proposed structure.

E.1-(4-Chloro-2-fluoro-5-hydroxyphenyl)-3-methyl-4-difluoromethyl-Δ.sup.2-1,2,4-triazolin-5-one

A stirred solution of 4.6 g (0.015 mole) of1-(4-chloro-2-fluoro-5-methoxyphenyl)-3-methyl-4-difluoromethyl-Δ.sup.2-1,2,4-triazoline-5-one in 200 mL of methylene chloride was cooled to10° C., and a solution of 11.2 g (0.045 mole) of boron tribromide in 45mL of methylene chloride was added. Upon complete addition, the coolingbath was removed, and the reaction mixture was stirred for four hours,as it warmed to ambient temperature. Water (100 mL) was added andstirring was continued for an additional 18 hours. The organic layer wasseparated, dried over magnesium sulfate, and filtered. The filtrate wasconcentrated under reduced pressure to give 4.4 g of1-(4-chloro-2-fluoro-5-hydroxyphenyl-3-methyl-4-difluoromethyl-Δ.sup.2-1,2,4-triazolin-5-one; mp 147°-152° C.

The nmr spectrum was consistent with the proposed structure.

EXAMPLE 2 Preparation of1-(4-Chloro-2-Fluoro-5-Propargyloxyphenyl)-3-Methyl-4-Difluoromethyl-.DELTA.²-1,2,4-Triazolin-5-One

To a stirred mixture of 0.7 g (0.0023 mole) of1-(4-chloro-2-fluoro-5-hydroxyphenyl)-3-methyl-4-difluoromethyl-Δ.sup.2-1,2,4-triazolin-5-one and 0.2 g (0.0015 mole) of potassium carbonate in50 mL of acetone was added 0.3 g (0.0025 mole) of propargyl bromide.Upon complete addition, the reaction mixture was heated at reflux forthree hours, then concentrated under reduced pressure. The residue wasdissolved in methylene chloride and washed with water and aqueous 10%sodium hydroxide. The organic layer was dried over magnesium sulfate andfiltered. The filtrate was concentrated under reduced pressure to give0.33 g of1-(4-chloro-2-fluoro-5-propargyloxyphenyl)-3-methyl-4-difluoromethyl-.DELTA.²-1,2,4-triazolin-5-one as an oil. A sample of this material was employedin the herbicidal efficacy tests described below.

The nmr spectrum was consistent with the proposed structure.

The reaction above was repeated with a purer sample of1-(4-chloro-2-fluoro-5-hydroxyphenyl)-3-methyl-4-difluoromethyl-Δ.sup.2-1,2,4-triazolin-5-one (mp 158°-162° C.) to give the desiredpropargyloxy derivative as a solid, mp 75°-78° C.

The nmr spectrum was consistent with the proposed structure.

A sample of product prepared in a similar manner was purified formicroanalysis, mp 82°-85° C.

Analysis calc'd for C₁₃ H₉ ClF₃ N₃ O₂ : C 47.07, H 2.73, N 12.67; Found:C 46.86, H 2.47, N 12.48.

EXAMPLE 3 Preparation of1-[4-Chloro-2-Fluoro-5-(1-Methylethoxy)Phenyl]-3-Methyl-4-Difluoromethyl-.DELTA.²-1,2,4-Triazolin-5-One

This compound was prepared in a manner analogous to Example 2 using 0.50g (0.0017 mole) of1-(4-chloro-2-fluoro-5-hydroxyphenyl)-3-methyl-4-difluoromethyl-Δ.sup.2-1,2,4-triazolin-5-one, 0.36 g (0.0021 mole) of 2-iodopropane, and 0.71g (0.0051 mole) of potassium carbonate in 50 mL of acetone. The yield of1-[4-chloro-2-fluoro-5-(1-methylethoxy)phenyl]-3-methyl-4-difluoromethyl-.DELTA.²-1,2,4-triazolin-5-one was 0.40 g; m.p. 77°-79° C.

The nmr spectrum was consistent with the proposed structure.

EXAMPLE 4 Preparation of1-[4-Chloro-2-Fluoro-5-(1-Methyl-2-Propynyloxy)Phenyl]-3-Methyl-4-Difluoromethyl-Δ²-1,2,4-Triazolin-5-One

This compound was prepared in a manner analogous to Example 2 using 0.50g (0.0017 mole) of1-(4-chloro-2-fluoro-5-hydroxyphenyl)-3-methyl-4-difluoromethyl-Δ.sup.2-1,2,4-triazolin-5-one, 0.28 g (0.0021 mole) of 3-bromo-1-butyne, and0.36 g (0.0021 mole) of potassium carbonate in 50 mL of acetone. Theyield of1-[4-chloro-2-fluoro-5-(1-methyl-2-propynyloxy)phenyl]-3-methyl-4-difluoromethyl-Δ²-1,2,4-triazolin-5-one, as an oil, was 0.35 g.

The nmr spectrum was consistent with the proposed structure.

Analysis calc'd for C₁₄ H₁₁ ClF₃ N₃ O₂ : C 48.64, H 3.21, N 12.15;Found: C 48.39, H 3.32, N 11.95.

EXAMPLE 5 Preparation of1-(4-Chloro-2-Fluoro-5-Methoxymethoxyphenyl)-3-Methyl-4-Difluoromethyl-.DELTA.²-1,2,4-Triazolin-5-One

This compound was prepared in the manner of Example 2 using 0.75 g(0.0026 mole) of1-(4-chloro-2-fluoro-5-hydroxyphenyl)-3-methyl-4-difluoromethyl-Δ.sup.2-1,2,4-triazolin-5-one, 0.21 g (0.026 mole) of chloromethyl methylether, and 0.35 g (0.0026 mole) of potassium carbonate in 60 mL ofacetone. The yield of1-[4-chloro-2-fluoro-5-methoxymethoxyphenyl]-3-methyl-4-difluoromethyl-.DELTA.²-1,2,4-triazolin-5-one, as an oil, was 0.84 g.

The nmr spectrum was consistent with the proposed structure.

Analysis calc'd for C₁₂ H₁₁ ClF₃ N₃ O₃ : C 42.68, H 3.28, N 12.44;Found: C 42.59; H 3.42, N 12.33.

EXAMPLE 6 Preparation of1-(4-Chloro-2-Fluoro-5-Allyloxyphenyl)-3-Methyl-4-Difluoromethyl-Δ.sup.2-1,2,4-Triazolin-5-One

This compound was prepared in the manner of Example 2 using 0.75 g(0.0026 mole) of1-(4-chloro-2-fluoro-5-hydroxyphenyl)-3-methyl-4-difluoromethyl-Δ.sup.2-1,2,4-triazolin-5-one, 0.31 g (0.0026 mole) of allyl bromide, and 0.35g (0.0026 mole) of potassium carbonate in 60 mL of acetone. The yield of1-(4-chloro-2-fluoro-5-allyloxyphenyl)-3-methyl-4-difluoromethyl-Δ.sup.2-1,2,4-triazolin-5-one was 0.85 g; m.p. 53°-55° C.

The nmr spectrum was consistent with the proposed structure.

Analysis calc'd for C₁₃ H₁₁ ClF₃ N₃ O₂ : C 46.64, H 3.21, N 12.45;Found: C 46.79, H 3.32, N 12.59.

EXAMPLE 7 Preparation of1-[4-Chloro-2-Fluoro-5-(1-Methyl-2-Methoxyethoxy)Phenyl]-3-Methyl-4-Difluoromethyl-Δ²-1,2,4-Triazolin-5-one

A stirred mixture of 0.45 g (0.0015 mole) of1-(4-chloro-2-fluoro-5-hydroxyphenyl)-3-methyl-4-difluoromethyl-Δ.sup.2-1,2,4-triazolin-5-one and 0.41 g (0.0017 mole) of sodium hydride in 8mL of dimethylformamide was warmed to 90° C. The reaction was cooled to40° C., and 0.37 g (0.0015 mole) of the tosylate of methoxypropan-2-olwas added in one portion. The reaction mixture was heated attemperatures varying from 40° to 140° C., then was allowed to cool toambient temperature and was stirred for 16 hours. The reaction mixturewas partitioned between water and methylene chloride. The methylenechloride layer was washed sequentially with aqueous 10% sodiumhydroxide, aqueous 10% hydrochloric acid, and water. The organic layerwas dried with magnesium sulfate and filtered. The filtrate wasconcentrated under reduced pressure to give 0.38 g of1-[4-chloro-2-fluoro-5-(1-methyl-2-methoxyethoxy)phenyl]-3-methyl-4-difluoromethyl-Δ² -1,2,4-triazolin-5-one as an oil.

The nmr spectrum was consistent with the proposed structure.

EXAMPLE 8 Preparation of1-(4-Bromo-2-Fluoro-5-Methoxyphenyl)-3-Methyl-4-Difluoromethyl-Δ.sup.2-1,2,4-Triazolin-5-One Step A. 2-Bromo-4-fluorophenyl methyl carbonate

A stirred solution of 561 g (5.0 moles) of 4-fluorophenol in 600 mL ofdioxane was cooled in an ice-water bath and 831 g (5.2 moles) of brominewas added dropwise. The complete addition required 1.5 hours, duringwhich the reaction mixture temperature was maintained at 14°-25° C.Following the addition, the ice-water bath was removed, and the reactionmixture temperature rose to 35° C. The reaction mixture was stirred fortwo hours, then 600 mL of water, followed by 420 mL of 10.8N aqueoussodium hydroxide were added dropwise over 30 minutes and 1 hourrespectively. Upon complete addition, the reaction mixture was cooled to0°-10° C., and 591 g (6.15 moles) of methyl chloroformate was addeddropwise over four hours. Upon complete addition, the reaction mixturewas allowed to warm to ambient temperature and was stirred for 17 hours.After this time, 450 g of aqueous 50% sodium hydroxide was added toneutralize the reaction mixture. The resultant solid was collected byfiltration, and the filter cake washed with two 500 mL portions ofwater. The solid was dried under reduced pressure to give 1211 g of2-bromo-4-fluorophenyl methyl carbonate; m.p. 75°-78° C.

The nmr spectrum was consistent with the proposed structure.

Step B. 2-Bromo-4-fluoro-5-nitrophenyl methyl carbonate

A rapidly stirred solution of 946 g (3.8 moles) of2-bromo-4-fluorophenyl methyl carbonate in 1292 mL of sulfuric acid wascooled to 5°-10° C., and 368 g (4.18 moles) of 70% nitric acid was addeddropwise over two hours. Upon complete addition, the reaction mixturewas allowed to warm to ambient temperature and was stirred for twohours. The reaction mixture was poured into 5000 mL of ice water. Anymaterial remaining in the reaction vessel was washed into the ice-waterwith 750 mL of water. The resultant solid was collected by filtrationand washed with 1000 mL of water. The solid was dried with mild heatunder reduced pressure to give 1031 g of 2-bromo-4-fluoro-5nitrophenylmethyl carbonate.

The nmr spectrum was consistent with the proposed structure.

Step C. 2-Bromo-4-fluoro-5-nitrophenol

A stirred solution of 1031 g (3.5 moles) of2-bromo-4-fluoro-5-nitrophenyl methyl carbonate in 300 mL of 2.3Naqueous sodium hydroxide was heated to reflux and stirred for threehours. The hot reaction mixture was filtered through diatomaceous earth.Any material remaining in the reaction vessel was washed onto the filtercake with 1000 mL of water. The filtrate was cooled to 8°-10° C., and560 mL of concentrated hydrochloric acid was added, with stirring, overone hour. The resultant solid was collected by filtration. Any materialremaining in the reaction vessel was washed onto the filter cake with1000 mL of water. The dried filter cake was recrystallized from tolueneto give, in two crops, 543 g of 2-bromo-4-fluoro-5-nitrophenol, m.p.124°-126° C.

The nmr spectrum were consistent with the proposed structure.

Step D. 4-Bromo-2-fluoro-5-methoxynitrobenzene

A stirred solution of 30.0 g (0.127 mole) of2-bromo-4-fluoro-5-nitrophenol, 26.9 g (0.19 mole) of methyl iodide, and26.3 g (0.19 mole) of potassium carbonate in 200 mL of acetone washeated at reflux for five hours. The reaction mixture was filtered, andthe filtrate concentrated under reduced pressure to give a residue. Theresidue was dissolved in methylene chloride and passed through a columnof silica gel. The elute was concentrated under reduced pressure to give30 g of 4-bromo-2-fluoro-5-methoxynitrobenzene; m.p. 74°-76° C.

Step E. 4-Bromo-2-fluoro-5-methoxyaniline

To a stirred solution of 30.0 g (0.12 mole) of4-bromo-2-fluoro-5-methoxynitrobenzene in 200 mL of acetic acid wasadded 40 mL of water, followed by the portionwise addition of 30.0 g(0.54 mole) of iron filings during a 2.5 hour period. Upon completeaddition, the reaction mixture was stirred at 25°-35° C. for one hour.Diethyl ether, 200 mL, was added, and the reaction mixture was filteredthrough a pad of diatomaceous earth. The filtrate was washed with 200 mLof water. The organic layer was separated and neutralized with solidsodium bicarbonate. The mixture was dried with magnesium sulfate andfiltered. The filtrate was concentrated under reduced pressure to give aresidual solid. The solid was recrystallized from petroleum ether togive 23.5 g of 4-bromo-2-fluoro-5-methoxyaniline; m.p. 60°-62° C.

Step F. Pyruvic acid, 4-bromo-2-fluoro-5-methoxyphenylhdrazone

Under a nitrogen atmosphere, a stirred solution of 23.5 g (0.107 mole)of 4-bromo-2-fluoro-5-methoxyaniline in 150 mL of concentratedhydrochloric acid was cooled to -9° C., and a solution of 7.4 g (0.107mole) of sodium nitrite in 40 mL of water was added dropwise over twohours. Upon complete addition, the reaction mixture was stirred at -9°C. for 45 minutes, then a solution of 36.0 g (0.160 mole) of stannouschloride in 50 mL of concentrated hydrochloric acid was added dropwiseover one hour. The reaction mixture temperature was maintained at -9° to0° C. throughout the addition. Upon complete addition, the reactionmixture was allowed to warm to ambient temperature and was stirred fortwo hours. After this time, 100 mL of water was added to the reactionmixture, followed by the dropwise addition of a solution of 9.4 g (0.107mole) of pyruvic acid in 100 mL of water. Upon complete addition, thereaction mixture was stirred for 30 minutes at ambient temperature. Thereaction mixture was filtered to collect a solid. The solid was dried togive 23.5 g of pyruvic acid, 4-bromo-2-fluoro-5-methoxyphenylhydrazone;m.p. 156°-158° C.

Step G. 1-(4-Bromo-2-fluoro-5-methoxyphenyl)-3-methyl-Δ²-1,2,4-triazolin-5-one

A stirred solution of 22.7 g (0.074 mole) of pyruvic acid,4-bromo-2-fluoro-5-methoxyphenylhydrazone, 20.5 g (0.074 mole) ofdiphenylphosphoryl azide, and 7.5 g (0.074 mole) of triethylamine in 150mL of toluene was heated at a reflux for four hours. The reactionmixture was cooled and diluted with diethyl ether. The mixture wasextracted three times with aqueous 1 molar sodium hydroxide. Thecombined extracts were washed with diethyl ether and made acidic withconcentrated hydrochloric acid. The resultant solid was collected byfiltration and washed with water. The solid was dried to give 15.0 g of1-(4-bromo-2-fluoro-5-methoxyphenyl)-3-methyl-Δ² -1,2,4-triazolin-5-one.

The nmr spectrum was consistent with the proposed structure.

H.1-(4-Bromo-2-fluoro-5-methoxyphenyl)-3-methyl-4-difluoromethyl-Δ.sup.2-1,2,4-triazolin-5-one

A stirred solution of 15.0 g (0.050 mole) of1-(4-bromo-2-fluoro-5-methoxyphenyl)-3-methyl-Δ² -1,2,4-triazolin-5-one,5.6 g (0.10 mole) of potassium hydroxide, and 1.6 g (0.005 mole) oftetrabutylammonium bromide in 150 mL of tetrahydrofuran was saturatedwith gaseous chlorodifluoromethane. The reaction mixture was stirred atambient temperature for 16 hours. An additional 2.9 g (0.052 mole) ofpotassium hydroxide was added, and the reaction mixture was againsaturated with chlorodifluoromethane. Upon complete saturation, thereaction mixture was stirred for two hours, then diluted with diethylether. The mixture was washed with water, then with aqueous saturatedsodium chloride. The organic layer was dried with sodium sulfate,filtered, and the filtrate concentrated under reduced pressure to give aresidue. The residue was subjected to column chromatography on silicagel. Elution was accomplished with 2:1 methylene chloride:petroleumether. The appropriate fractions were combined and concentrated underreduced pressure to give 4.2 g of1-(4-bromo-2-fluoro-5-methoxyphenyl)-3-methyl-4-difluoromethyl-Δ.sup.2-1,2,4-triazolin-5-one; m.p. 129°-130° C.

The nmr and the ir spectra were consistent with the proposed structure.

Analysis calc'd for C₁₁ H₉ BrF₃ N₃ O₂ : C37.52, H 2.58, N 11.93; Found:C37.38, H 2.35, N 11.52.

EXAMPLE 9 Preparation of1-(4-Bromo-2-Fluoro-5-Methoxymethoxyphenyl)-3-Methyl-4-Difluoromethyl-.DELTA.²-1,2,4-Triazolin-5-One Step A.1-(4-Bromo-2-fluoro-5-hydroxyphenyl)-3-methyl-4-difluoromethyl-Δ.sup.2-1,2,4-triazolin-5-one

A stirred solution of 7.3 g (0.029 mole) of boron tribromide in 30 mL ofmethylene chloride was cooled to -40° C., and a solution of 3.0 g (0.009mole) of1-(4-bromo-2-fluoro-5-methoxyphenyl)-3-methyl-4-difluoromethyl-Δ.sup.2-1,2,4-triazolin-5-one (Example 8) in 25 mL of methylene chloride wasadded dropwise. The reaction mixture temperature was maintained at -40°C. throughout the addition. Upon complete addition, the reaction mixturewas allowed to warm to ambient temperature and was stirred for 16 hours.The reaction mixture was poured into ice-water, and the mixtureextracted with diethyl ether. The extract was dried with sodium sulfate,filtered, and the filtrate concentrated under reduced pressure to give aresidue. The residue was dissolved in diethyl ether, and the solutionwas passed through a pad of silica gel. The eluate was concentratedunder reduced pressure to give 2.9 g of1-(4-bromo-2-fluoro-5-hydroxyphenyl)-3-methyl-4-difluoromethyl-Δ.sup.2-1,2,4-triazolin-5-one.

The nmr and the ir spectra were consistent with the proposed structure.

The nmr and the ir spectra were consistent with the proposed structure.

Step B.1-(4-2-fluoro-5-methoxymethoxyphenyl)-3-methyl-4-difluoromethyl-Δ.sup.2-1,2,4-triazolin-5-one

To a stirred suspension of 0.15 g (0.003 mole) of sodium hydride (50% inmineral oil) in 10 mL of toluene was slowly added 1.1 g (0.003 mole) of1-(4-bromo-2-fluoro-5-hydroxyphenyl)-3-methyl-4-difluoromethyl-Δ.sup.2-1,2,4-triazolin-5-one. N,N-dimethylacetamide (1-2 mL) was added and thereaction mixture was stirred at ambient temperature until it becameclear. The reaction was cooled to 20° C., and 0.8 g (0.006 mole) ofmethoxymethyl bromide was added. Upon complete addition, the reactionmixture was stirred at ambient temperature for 16 hours. The reactionmixture was poured onto ice and allowed to stand for one hour. Theorganic layer was separated and dried with magnesium sulfate. Themixture was filtered, and the filtrate subjected to columnchromatography on silica gel. Elution was accomplished with 4:1methylene chloride:heptane. The appropriate fractions were combined andconcentrated under reduced pressure to give 0.9 g of1-(4-bromo-2-fluoro-5-methoxymethoxyphenyl)-3-methyl-4-difluoromethyl-.DELTA.²-1,2,4-triazolin-5-one as an oil.

The nmr spectrum was consistent with the proposed structure.

Analysis calc'd for C₁₁ H₁₂ BrF₃ N₃ O₃ : C 37.72, H 2.89, N 10.99;Found: C 38.32, H 2.86, N 10.91.

EXAMPLE 10 Preparation of1-(4-Bromo-2-Fluoro-5-Propargyloxyphenyl)-3-Methyl-4-Difluoromethyl-.DELTA.²-1,2,4-Triazolin-5-one

A stirred solution of 2.5 g (0.008 mole) of1-(4-bromo-2-fluoro-5-hydroxyphenyl)-3-methyl-4-difluoromethyl-Δ.sup.2-1,2,4-triazolin-5-one (prepared as in Step A, Example 9), 1.6 g (0.012mole) of potassium carbonate, and 1.9 g (0.017 mole) of propargylbromide in 30 mL of acetone was heated at reflux for 16 hours. Thereaction mixture was cooled and concentrated under reduced pressure togive a residue. The residue was dissolved in methylene chloride andsubjected to column chromatography on silica gel. Elution wasaccomplished using methylene chloride. The appropriate fractions werecombined and concetrated under reduced pressure to give 2.3 g of1-(4-bromo-2-fluoro-5-propargyloxyphenyl)-3-methyl-4-difluoromethyl-.DELTA.²-1,2,4-triazolin-5-one; m.p. 70°-72° C.

The nmr spectrum was consistent with the proposed structure.

Analysis calc'd for C₁₃ H₉ BrF₃ N₃ O₂ : C 41.51, H 2.41, N 11.17; Found:C 41.33, H 2.19, N 11.35.

the following compounds were prepared from1-(4-bromo-2-fluoro-5-hydroxyphenyl)-3-methyl-4-difluoromethyl-Δ.sup.2-1,2,4-triazolin-5-one (Example 9A) by an alkylation procedure analogousto that described above in either Example 9B or Example 10:

EXAMPLE 11

1-(4-bromo-2-fluoro-5-ethoxyphenyl)-3-methyl-4-difluoromethyl-Δ²-1,2,4-triazolin-5-one, m.p. 106°-108° C. The ir and nmr spectra wereconsistent with the proposed structure.

Analysis calc'd for C₁₂ H₁₁ BrF₃ N₃ O₂ : C 39.36, H 3.03, N 11.48;Found: C 39.65, H 2.82, N 11.22.

EXAMPLE 12

1-[4-bromo-2-fluoro-5-(1-methylethoxy)-phenyl]-3-methyl-4-difluoromethyl-.DELTA.²-1,2,4-triazolin-5-one, obtained as an oil. The ir and nmr spectra wereconsistent with the proosed structure.

Analysis calc'd for C₁₃ H₁₃ BrF₃ N₃ O₂ : C 41.07, H 3.45, N 11.05;Found: C 41.03, H 3.19, N 10.93.

EXAMPLE 13

1-[4-bromo-2-fluoro-5-(1-methyl-propargyloxy)phenyl]-3-methyl-4-difluoromethyl-Δ²-1,2,4-triazolin-5-one, m.p. 80°-82° C. The ir and nmr spectra wereconsistent with the proposed structure.

Analysis calc'd for C₁₄ H₁₁ BrF₃ N₃ O₂ : C 43.10, H 2.84, N 10.76;Found: C 43.32, H 2.83, N 10.54.

EXAMPLE 14

1-[4-bromo-2-fluoro--5-(2-methoxyethoxy)phenyl]-3-methyl-4-difluoromethyl-.DELTA.²-1,2,4-triazolin-5-one, m.p. 81°-82° C. The ir and nmr spectra wereconsistent with the proposed structure.

Anaysis calc'd for C₁₃ H₁₃ BrF₃ N₃ O₃ : C 39.41, H 3.31, N 10.61; Found:C 39.25, H 3.08, N 10.31.

Herbicidal Activity

Comparative herbicidal efficacy data are given in Tables 1-5 below forthe present compound of Example 2 and the 2-chloro analog of thatcompound. The 2-chloro compound is1-(2,4-dichloro-5-propargyloxyphenyl)-3-methyl-4-difluoromethyl-Δ.sup.2-1,2,4-triazolin-5-one and is disclosed in British Pat. No. 2,090,250,supra. While the present compound of Example 2 differs structurally fromthe known compound only in having a fluorine atom instead of chlorine atthe C-2 position of the phenyl ring, it was markedly and unexpectedlymore active than the prior compound against a variety of broadleaf plantspecies in both preemergence and postemergence applications inside-by-side tests conducted as described below. Herbicidal data for thecompounds of Examples 3-14 are given in Tables 6 and 7.

The plant species employed in these tests were selected from thefollowing:

    ______________________________________                                        Common Name (Abbrev.)                                                                             Scientific Name                                           ______________________________________                                        Barnyardgrass (Barngr)                                                                            Echinochloa crus galli                                    Field Bindweed (Bindweed)                                                                         Convovulus arvensis                                       Blue Panicum (Blue Pan)                                                                           Panicum antidotale                                        Common Cocklebur (Coclebr)                                                                        Xanthium pensylvanicum                                    Field Corn (Corn)   Zea mays                                                  Cotton              Gossypium hirsutum                                        Giant Foxtail (Giantfox)                                                                          Setaria faberi Herrm.                                     Green Foxtail (Greenfox)                                                                          Setaria viridis                                           Ivyleaf Morningglory (Ivyglory)                                                                   Ipomoea hederacea (L.)                                                        or Ipomoea lacumosa                                       Johnsongrass (Johngr)                                                                             Sorghum halepense                                         Rice                Oryza sativa                                              Hemp Sesbania (Sesbania)                                                                          Sesbania exaltata Raf.                                    Sicklepod (Sicklepd)                                                                              Cassia obtusifolia L.                                     Broadleaf Signalgrass (Signalgr)                                                                  Brachiaria platyphylla                                    Soybean             Glycine max                                               Velvetleaf (Velvetlf)                                                                             Abutilon theophrasti                                      Wheat               Triticum aestivum                                         Wild Mustard (Wmustard)                                                                           Brassica kaber                                            Yellow Nutsede (Yel Nuts)                                                                         Cyperus esculentus                                        Yellow Foxtail Yellowfox)                                                                         Setaria lutescens                                                             (Weigel) Hubb.                                            ______________________________________                                    

Seeds or tubers of the plant test species were plant in furrows in steamsterilized sandy loam soil contained in disposable fiber flats. Theflats had been filled to a depth of about 6.5 cm with the soil. Atopping soil of equal portions of sand and sandy loam soil was placeduniformly on top of each flat to a depth of approximately 0.5 cm.

The flats for the preemergence tests were watered, then drenched withthe appropriate amount of a solution of the test compound in a mixtureof acetone and water containing a small amount (up to 0.5% v/v) ofsorbitan monolaurate emulsifer/solubilizer. The concentration of thetest compound in solution was varied to give a range of applicationrates, generally 8.0 kg/ha and submultiples thereof. The flats wereplaced in a greenhouse and watered regularly at the soil surface for 21days at which time phytotoxicity data were recorded.

The flats for the postemergence tests were placed in a greenhouse andwatered for 8-10 days, then the foliage of the emerged test plants wassprayed with a solution of the test compound in acetone-water containingup to 0.5% sorbitan monolaurate. After spraying, the foliage was keptdry for 24 hours, then watered regularly for 21 days, and phytotoxicitydata recorded.

Herbicidal data are given in Tables 1 and 2 below for the presentcompound of Example 2 (Compound 2) and for1-(2,4-dichloro-5-propargyloxyphenyl)-3-methyl-4-difluoromethyl-Δ.sup.2-1,2,4-triazolin-5-one (Compound A). IN these tables "V" is vigor, "K"is % kill, and "kg/ha" is kilograms per hectare. Vigor ratings vary from0 to 5 and have the following meaning:

V=5=no chemical injury; plants normal

4=slight injury; plants will or have already recovered

3=moderate injury; plants expected to recover

2=moderate to severe injury; plants are not expected to recover

1=severe injury; plants will not recover

0=dead plant

                                      TABLE 1                                     __________________________________________________________________________    Preemergence Activity                                                                 Rate of Application (kg/ha)                                                   .5000                                                                              .2500                                                                              .1250                                                                              .0625                                                                              .0313                                                                              .0156                                        Species V K  V K  V K  V K  V K  V K                                          __________________________________________________________________________    Compound 2                                                                    BARNGR  0 100                                                                              0 100                                                                              0 100                                                                              0 100                                                                              0 100                                                                              0 100                                        BINDWEED                                                                              0 100                                                                              0 100                                                                              0 100                                                                              4 90 4 80 4 70                                         BLUE PAN                                                                              0 100                                                                              0 100                                                                              0 100                                                                              0 100                                                                              0 100                                                                              0 100                                        COCKLEBR                                                                              0 100                                                                              2 90 2 90 3 30 3 0  5 0                                          CORN    0 100                                                                              0 100                                                                              0 100                                                                              0 100                                                                              0 100                                                                              3 70                                         COTTON  3 80 3 80 4 30 4 0  5 0  4 0                                          GIANTFOX                                                                              0 100                                                                              0 100                                                                              0 100                                                                              0 100                                                                              0 100                                                                              0 100                                        GREENFOX                                                                              0 100                                                                              0 100                                                                              0 100                                                                              0 100                                                                              0 100                                                                              0 100                                        IVYGLORY                                                                              0 100                                                                              0 100                                                                              0 100                                                                              3 90 3 70 3 0                                          JOHNGR  0 100                                                                              0 100                                                                              0 100                                                                              0 100                                                                              0 100                                                                              0 100                                        RICE    0 100                                                                              0 100                                                                              0 100                                                                              0 100                                                                              2 90 3 40                                         SESBANIA                                                                              0 100                                                                              0 100                                                                              3 90 0 100                                                                              3 50 4 0                                          SICKLEPD                                                                              0 100                                                                              0 100                                                                              1 95 3 10 4 0  4 0                                          SIGNALGR                                                                              0 100                                                                              0 100                                                                              0 100                                                                              0 100                                                                              0 100                                                                              3 80                                         SOYBEAN 0 100                                                                              0 100                                                                              0 100                                                                              0 100                                                                              3 90 3 80                                         VELVETLF                                                                              0 100                                                                              0 100                                                                              0 100                                                                              0 100                                                                              0 100                                                                              0 100                                        WHEAT   0 100                                                                              0 100                                                                              0 100                                                                              2 80 3 20 3 20                                         WMUSTARD                                                                              0 100                                                                              0 100                                                                              0 100                                                                              0 100                                                                              4 50 5 0                                          YEL NUTS                                                                              0 100                                                                              2 60 2 70 3 60 3 10 4 0                                          YELLOWFOX                                                                             0 100                                                                              0 100                                                                              0 100                                                                              0 100                                                                              0 100                                                                              3 70                                         Compound A*                                                                   BARNGR  0 100                                                                              0 100                                                                              0 100                                                                              0 100                                                                              0 100                                                                              0 100                                        BINDWEED                                                                              0 100                                                                              0 100                                                                              4 0  4 0  5 0  5 0                                          BLUE PAN                                                                              0 100                                                                              0 100                                                                              0 100                                                                              0 100                                                                              0 100                                                                              0 100                                        COCKLEBR                                                                              3 90 3 80 4 80 4 80 5 0  5 0                                          CORN    0 100                                                                              0 100                                                                              0 100                                                                              0 100                                                                              2 70 2 70                                         COTTON  3 50 4 80 4 0  5 0  4 80 4 0                                          GIANTFOX                                                                              0 100                                                                              0 100                                                                              0 100                                                                              0 100                                                                              0 100                                                                              0 100                                        GREENFOX                                                                              0 100                                                                              0 100                                                                              0 100                                                                              0 100                                                                              0 100                                                                              0 100                                        IVYGLORY                                                                              0 100                                                                              0 100                                                                              3 50 4 0  4 0  5 0                                          JOHNGR  0 100                                                                              0 100                                                                              0 100                                                                              0 100                                                                              0 100                                                                              0 100                                        RICE    0 100                                                                              0 100                                                                              0 100                                                                              1 95 0 100                                                                              0 100                                        SESBANIA                                                                              0 100                                                                              0 100                                                                              3 90 0 100                                                                              3 30 4 0                                          SICKLEPD                                                                              2 90 3 0  4 0  4 0  4 0  4 0                                          SIGNALGR                                                                              0 100                                                                              0 100                                                                              0 100                                                                              0 100                                                                              0 100                                                                              0 100                                        SOYBEAN 0 100                                                                              0 100                                                                              2 90 3 80 4 60 4 0                                          VELVETLF                                                                              0 100                                                                              0 100                                                                              0 100                                                                              0 100                                                                              0 100                                                                              0 100                                        WHEAT   0 100                                                                              0 100                                                                              0 100                                                                              3 70 3 50 4 0                                          WMUSTARD                                                                              0 100                                                                              0 100                                                                              4 0  5 0  5 0  5 0                                          YEL NUTS                                                                              0 100                                                                              2 80 2 60 3 40 3 0  4 0                                          YELLOWFOX                                                                             0 100                                                                              0 100                                                                              0 100                                                                              0 100                                                                              0 100                                                                              3 95                                         __________________________________________________________________________     *Compound A is                                                                1(2,4-dichloro-5-propargyloxyphenyl)-3-methyl-4-difluoromethyl-Δ.su    .21,2,4-triazolin-5-one.                                                  

                                      TABLE 2                                     __________________________________________________________________________    Postemergence Activity                                                                Rate of Applications (kg/ha)                                                  .5000                                                                              .2500                                                                              .1250                                                                              .0625                                                                              .0313                                                                              .0156                                        Species V K  V K  V K  V K  V K  V K                                          __________________________________________________________________________    Compound 2                                                                    BARNGR  0 100                                                                              0 100                                                                              0 100                                                                              0 100                                                                              0 100                                                                              3 80                                         BINDWEED                                                                              0 100                                                                              0 100                                                                              0 100                                                                              0 100                                                                              0 100                                                                              3 90                                         BLUE PAN                                                                              0 100                                                                              0 100                                                                              0 100                                                                              0 100                                                                              0 100                                                                              2 90                                         COCKLEBR                                                                              0 100                                                                              2 90 3 90 4 0  5 0  5 0                                          CORN    0 100                                                                              0 100                                                                              0 100                                                                              1 60 2 30 2 60                                         COTTON  0 100                                                                              0 100                                                                              0 100                                                                              3 90 0 100                                                                              1 90                                         GIANTFOX                                                                              0 100                                                                              0 100                                                                              0 100                                                                              0 100                                                                              0 100                                                                              0 100                                        GREENFOX                                                                              0 100                                                                              0 100                                                                              0 100                                                                              0 100                                                                              0 100                                                                              2 90                                         IVYGLORY                                                                              0 100                                                                              0 100                                                                              0 100                                                                              0 100                                                                              0 100                                                                              2 80                                         JOHNGR  0 100                                                                              0 100                                                                              0 100                                                                              0 100                                                                              4 30 3 60                                         RICE    0 100                                                                              0 100                                                                              0 100                                                                              0 100                                                                              1 90 3 70                                         SESBANIA                                                                              0 100                                                                              0 100                                                                              0 100                                                                              0 100                                                                              0 100                                                                              2 90                                         SICKLEPD                                                                              0 100                                                                              0 100                                                                              1 90 0 100                                                                              3 30 3 40                                         SIGNALGR                                                                              0 100                                                                              0 100                                                                              0 100                                                                              0 100                                                                              0 100                                                                              2 90                                         SOYBEAN 1 90 0 100                                                                              1 90 2 70 3 60 3 30                                         VELVETLF                                                                              0 100                                                                              0 100                                                                              0 100                                                                              0 100                                                                              0 100                                                                              0 100                                        WHEAT   0 100                                                                              0 100                                                                              0 100                                                                              2 70 4 30 5 0                                          WMUSTARD                                                                              0 100                                                                              0 100                                                                              0 100                                                                              0 100                                                                              3 70 5 0                                          YEL NUTS                                                                              2 80 0 100                                                                              2 60 2 20 3 0  5 0                                          YELLOWFOX                                                                             0 100                                                                              0 100                                                                              0 100                                                                              0 100                                                                              0 100                                                                              0 100                                        Compound A*                                                                   BARNGR  0 100                                                                              0 100                                                                              0 100                                                                              3 80 3 70 0 100                                        BINDWEED                                                                              0 100                                                                              0 100                                                                              0 100                                                                              4 60 4 0  0 100                                        BLUE PAN                                                                              0 100                                                                              0 100                                                                              0 100                                                                              0 100                                                                              0 100                                                                              0 100                                        COCKLEBR                                                                              2 0  3 0  4 0  3 0  5 0  5 0                                          CORN    0 100                                                                              0 100                                                                              0 100                                                                              2 90 4 0  4 60                                         COTTON  0 100                                                                              0 100                                                                              0 100                                                                              0 100                                                                              0 100                                                                              3 30                                         GIANTFOX                                                                              0 100                                                                              0 100                                                                              0 100                                                                              0 100                                                                              0 100                                                                              0 100                                        GREENFOX                                                                              0 100                                                                              0 100                                                                              0 100                                                                              0 100                                                                              0 100                                                                              0 100                                        IVYGLORY                                                                              0 100                                                                              0 100                                                                              0 100                                                                              1 90 1 90 4 90                                         JOHNGR  0 100                                                                              0 100                                                                              0 100                                                                              0 100                                                                              4 30 1 90                                         RICE    0 100                                                                              0 100                                                                              0 100                                                                              0 100                                                                              1 90 2 90                                         SESBANIA                                                                              0 100                                                                              0 100                                                                              0 100                                                                              0 100                                                                              0 100                                                                              2 90                                         SICKLEPD                                                                              0 100                                                                              0 100                                                                              0 100                                                                              5 0  4 80 5 0                                          SIGNALGR                                                                              0 100                                                                              0 100                                                                              0 100                                                                              0 100                                                                              0 100                                                                              0 100                                        SOYBEAN 2 90 2 80 3 40 3 30 4 0  4 0                                          VELVETLF                                                                              0 100                                                                              0 100                                                                              0 100                                                                              0 100                                                                              2 90 0 100                                        WHEAT   0 100                                                                              3 80 2 70 4 10 4 20 5 0                                          WMUSTARD                                                                              0 100                                                                              3 20 5 0  5 0  5 0  5 0                                          YEL NUTS                                                                              2 90 2 60 3 0  3 30 4 0  4 0                                          YELLOWFOX                                                                             0 100                                                                              0 100                                                                              0 100                                                                              0 100                                                                              0 100                                                                              4 70                                         __________________________________________________________________________     *Compound A is                                                                1(2,4-dichloro-5-propargyloxyphenyl)-3-methyl-4-difluoromethyl-Δ.su    .21,2,4-triazolin-5-one.                                                  

In order to better compare herbicidal activity for the two testcompounds, biological efficacy (BE) figures were calculated from percentkill and vigor using the equation

    BE=% kill+X(100-% kill)

wherein X is a number assigned to the vigor rating according to thefollowing schedule:

    ______________________________________                                                vigor X                                                               ______________________________________                                                0     1                                                                       1     1                                                                       2     0.75                                                                    3     0.25                                                                    4     0.12                                                                    5     0                                                               ______________________________________                                    

Tables 3 and 4 below show BE values calculated from the data in Tables 1and 2 above for the present compound of Example 2 and the 2-chloroanalog. BE values increase with herbicidal efficacy to a maximum valueof 100.

                  TABLE 3                                                         ______________________________________                                        Preemergence Biological Efficacy (BE)                                                 Rate of Application (kg/ha)                                                     .5000  .2500   .1250 .0625 .0313 .0156                              Species   BE     BE      BE    BE    BE    BE                                 ______________________________________                                        Compound 2                                                                    BARNGR    100    100     100   100   100   100                                BINDWEED  100    100     100   91    82    74                                 BLUE PAN  100    100     100   100   100   100                                COCKLEBR  100    98      98    48    25    0                                  CORN      100    100     100   100   100   78                                 COTTON    85     85      38    12    0     12                                 GIANTFOX  100    100     100   100   100   100                                GREENFOX  100    100     100   100   100   100                                IVYGLORY  100    100     100   93    78    25                                 JOHNGR    100    100     100   100   100   100                                RICE      100    100     100   100   98    55                                 SESBANIA  100    100     93    100   63    12                                 SICKLEPD  100    100     100   33    12    12                                 SIGNALGR  100    100     100   100   100   85                                 SOYBEAN   100    100     100   100   93    85                                 VELVETLF  100    100     100   100   100   100                                WHEAT     100    100     100   95    40    40                                 WMUSTARD  100    100     100   100   56    0                                  YEL NUTS  100    90      93    70    33    12                                 YELLOWFOX 100    100     100   100   100   78                                 Compound A*                                                                   BARNGR    100    100     100   100   100   100                                BINDWEED  100    100     12    12    0     0                                  BLUE PAN  100    100     100   100   100   100                                COCKLEBR  93     85      82    82    0     0                                  CORN      100    100     100   100   93    93                                 COTTON    63     82      12    0     82    12                                 GIANTFOX  100    100     100   100   100   100                                GREENFOX  100    100     100   100   100   100                                IVYGLORY  100    100     63    12    12    0                                  JOHNGR    100    100     100   100   100   100                                RICE      100    100     100   100   100   100                                SESBANIA  100    100     93    100   48    12                                 SICKLEPD  98     25      12    12    12    12                                 SIGNALGR  100    100     100   100   100   100                                SOYBEAN   100    100     98    85    65    12                                 VELVETLF  100    100     100   100   100   100                                WHEAT     100    100     100   78    63    12                                 WMUSTARD  100    100     12    0     0     0                                  YEL NUTS  100    95      90    55    25    12                                 YELLOWFOX 100    100     100   100   100   96                                 ______________________________________                                         *Compound A is                                                                1(2,4-d1chloro-5-propargyloxyphenyl)-3-methyl-4-difluoromethyl-1/3.sup.21    2,4-triazolin-5-one.                                                      

                  TABLE 4                                                         ______________________________________                                        Postemergence Biological Efficacy                                                     Rate of Application (kg/ha)                                                     .5000  .2500   .1250 .0625 .0313 .0156                              Species   BE     BE      BE    BE    BE    BE                                 ______________________________________                                        Compound 2                                                                    BARNGR    100    100     100   100   100   85                                 BINDWEED  100    100     100   100   100   93                                 BLUE PAN  100    100     100   100   100   98                                 COCKLEBR  100    98      93    12    0     0                                  CORN      100    100     100   100   83    90                                 COTTON    100    100     100   93    100   100                                GIANTFOX  100    100     100   100   100   100                                GREENFOX  100    100     100   100   100   98                                 IVYGLORY  100    100     100   100   100   95                                 JOHNGR    100    100     100   100   38    70                                 RICE      100    100     100   100   100   78                                 SESBANIA  100    100     100   100   100   98                                 SICKLEPD  100    100     100   100   48    55                                 SIGNALGR  100    100     100   100   100   98                                 SOYBEAN   100    100     100   93    70    48                                 VELVETLF  100    100     100   100   100   100                                WHEAT     100    100     100   93    38    0                                  WMUSTARD  100    100     100   100   78    0                                  YEL NUTS  95     100     90    80    25    0                                  YELLOWFOX 100    100     100   100   100   100                                Compound A*                                                                   BARNGR    100    100      100  85    78    100                                BINDWEED  100    100     100   65    12    100                                BLUE PAN  100    100     100   100   100   100                                COCKLEBR  75     25      12    25    0     0                                  CORN      100    100     100   98    12    65                                 COTTON    100    100     100   100   100   48                                 GIANTFOX  100    100     100   100   100   100                                GREENFOX  100    100     100   100   100   100                                IVYGLORY  100    100     100   100   100   91                                 JOHNGR    100    100     100   100   38    100                                RICE      100    100     100   100   100   98                                 SESBANIA  100    100     100   100   100   98                                 SICKLEPD  100    100     100   0     82    0                                  SIGNALGR  100    100     100   100   100   100                                SOYBEAN   98     95      55    48    12    12                                 VELVETLF  100    100     100   100   98    100                                WHEAT     100    85      93    21    30    0                                  WMUSTARD  100    40      0     0     0     0                                  YEL NUTS  98     90      25    48    12    12                                 YELLOWFOX 100    100     100   100   100   74                                 ______________________________________                                         *Compound A is                                                                1(2,4-dichloro-5-propargyloxyphenyl)-3-methyl-4-difluoromethyl-Δ.su    .21,2,4-triazolin-5-one.                                                  

Table 5 below shows a comparison of the average or overall biologicalefficacy for the present compound of Example 2 and the prior artcompound against both weed grasses and weed broadleaves. The BE valuesfor grasses represent the average of the BE values in Table 3(preemergence) or Table 4 (postemergence) for barnyardgrass, bluepanicum, giant foxtail, green foxtail, johnsongrass, signalgrass, yellownutsedge, and yellow foxtail. The BE values for broadleaves representthe average for bindweed, cocklebur, ivyglory, sesbania, sicklepod,velvetleaf, and wild mustard. As can be seen from the table, bothcompounds performed equally well against the grasses, but the presentcompound was substantially more active against the more difficult tocontrol broadleaves. In the preemergence tests against broadleaves, 0.5kg/ha of the standard compound was needed for a BE of 99, whereas only0.125 kg/ha of the present compound was required for the same level ofcontrol. Similarly, in the postemergence tests, 0.5 kg/ha of thestandard gave a BE value of 96 while the present compound gave a BE of99 at one-fourth the application rate, 0.125 kg/ha.Thus, in eitherpreemergence or postemergence applications against the broadleaves, thepresent compound was about four times as active as the 2-chlorocompound.

                  TABLE 5                                                         ______________________________________                                        Average Biological Efficacy                                                             Rate of Application (kg/ha)                                                         0.50   0.25 0.125                                                                              0.0625                                                                              0.0313                                                                              0.0156                           Cpd. Species    BE     BE   BE   BE    BE    BE                               ______________________________________                                        Preemergence                                                                  2    Grasses    100    100  100  100   100   95                                    Broadleaves                                                                              100     99   99  81    59    32                               A*   Grasses    100    100  100  100   100   99                                    Broadleaves                                                                               99     87   68  45    25    18                               Postemergence                                                                 2    Grasses    100    100  100  100   91    93                                    Broadleaves                                                                              100     99   99  87    75    63                               A*   Grasses    100    100  100  98    88    96                                    Broadleaves                                                                               96     81   73  56    56    56                               ______________________________________                                         *Compound A is                                                                2,4dichloro-5-propargyloxyphenyl)-3-methyl-4-difluoromethyl-Δ.sup.2    ,2,4-triazolin-5-one.                                                     

For the compounds of Examples 3-4, phytotoxicity data were taken aspercent control. Percent control was determined by a method similar tothe 0 to 100 rating system disclosed in "Research Methods in WeedScience," 2nd ed., B. Truelove, Ed.; Southern Weed Science Society;Auburn University, Auburn, Ala., 1977. The present rating system is asfollows:

    ______________________________________                                        Rating Description                                                            Percent                                                                              of Main   Crop          Weed                                           Control                                                                              Categories                                                                              Description   Description                                    ______________________________________                                         0     No effect No crop reduction                                                                           No weed control                                                 or injury                                                    10               Slight discoloration                                                                        Very poor weed                                                  or stunting   control                                        20     Slight    Some discoloration,                                                                         Poor weed                                             effect    stunting or stand                                                                           control                                        30               Crop injury more                                                                            Poor to                                                         pronounced but not                                                                          deficient weed                                                  lasting       control                                        40               Moderate injury,                                                                            Deficient weed                                                  crop usually  control                                                         recovers                                                     50     Moderate  Crop injury more                                                                            Deficient to                                          effect    lasting, recovery                                                                           moderate weed                                                                 control                                        60               Lasting crop  Moderate weed                                                   injury no recovery                                                                          control                                        70               Heavy injury and                                                                            Control somewhat                                                stand loss    less than                                                                     satisfactory                                   80     Severe    Crop nearly   Satisfactory to                                                 destroyed a few                                                                             good weed                                                       survivors     control                                        90               Only occasional                                                                             Very good to                                                    live plants left                                                                            excellent control                              100    Complete  Complete crop Complete weed                                         effect    destruction   destruction                                    ______________________________________                                    

Herbicidal data at selected application rates are given for thecompounds of Examples 3-14 in Tables 6 and 7 below. The test compoundsare identified in the tables by Example numbers. In the tables "kg/ha"is kilograms per hectare and "% C" is percent control.

                                      TABLE 6                                     __________________________________________________________________________    Preemergence Activity                                                         Compound Number*                                                                         3  4  5  6  7  8   9   10  11  12  13  14                          Rate (kg/ha)                                                                             1.0                                                                              0.25                                                                             1.0                                                                              0.5                                                                              0.5                                                                              0.0625                                                                            0.0625                                                                            0.0625                                                                            0.0625                                                                            0.0625                                                                            0.0625                                                                            0.0625                      Species    % C                                                                              % C                                                                              % C                                                                              % C                                                                              % C                                                                              % C % C % C % C % C % C % C                         __________________________________________________________________________    Cotton      50                                                                               70                                                                              100                                                                               20                                                                               90                                                                               0   0  10   0   0  10  20                          Soybean    100                                                                              100                                                                              100                                                                               90                                                                              100                                                                              30  95  80  50  10  70  50                          Field Corn 100                                                                              100                                                                              100                                                                              100                                                                              100                                                                              100 100 95  80  80  80  90                          Rice       100                                                                              100                                                                               90                                                                              100                                                                              100                                                                              90  95  90  70  80  95  80                          Wheat      100                                                                              100                                                                              100                                                                              100                                                                              100                                                                              90  95  95  50  80  90  40                          Field Bindweed                                                                           100                                                                              100                                                                              100                                                                              100                                                                              100                                                                              --  95  --  --  --  90  --                          Morningglory                                                                             100                                                                              100                                                                              100                                                                              100                                                                              100                                                                              95  100 90  95  60  90  95                          Velvetleaf 100                                                                              100                                                                              100                                                                              100                                                                              100                                                                              100 100 100 100 100 100 100                         Barnyardgrass                                                                            100                                                                              100                                                                              100                                                                              100                                                                              100                                                                              100 100 100 100 80  100 95                          Green Foxtail                                                                            100                                                                              100                                                                              100                                                                              100                                                                              100                                                                              90  100 100 100 90  100 100                         Johnsongrass                                                                             100                                                                              100                                                                              100                                                                              100                                                                              100                                                                              90  95  100 100 90  100 90                          Yellow Nutsedge                                                                          100                                                                               40                                                                              100                                                                               80                                                                               90                                                                              80  --  80  70  10  --  90                          __________________________________________________________________________     *The compound number is the number of the Example in which the particular     compound was prepared.                                                   

                                      TABLE 7                                     __________________________________________________________________________    Postemergence Activity                                                        Compound Number*                                                                         3  4  5  6  7  8   9   10  12  13                                  Rate (kg/ha)                                                                             1.0                                                                              0.25                                                                             1.0                                                                              0.5                                                                              0.5                                                                              0.125                                                                             0.0625                                                                            0.0625                                                                            0.125                                                                             0.125                               Species    % C                                                                              % C                                                                              % C                                                                              % C                                                                              % C                                                                              % C % C % C % C % C                                 __________________________________________________________________________    Cotton     100                                                                              100                                                                              100                                                                              100                                                                              100                                                                              70   80 50  80  80                                  Soybean    100                                                                               90                                                                              100                                                                               90                                                                               80                                                                              90   95 95  80  90                                  Field Corn  70                                                                               90                                                                              100                                                                               30                                                                               80                                                                              90  100 100 80  90                                  Rice        90                                                                              100                                                                              100                                                                               30                                                                              100                                                                              80  100 90  80  95                                  Wheat       60                                                                              100                                                                              100                                                                               30                                                                               90                                                                              80   95 50  50  95                                  Field Bindweed                                                                           100                                                                              100                                                                              100                                                                              100                                                                              100                                                                              --  100 95  90  100                                 Morningglory                                                                             100                                                                              100                                                                              100                                                                              100                                                                              100                                                                              100 100 100 80  100                                 Velvetleaf 100                                                                              100                                                                              100                                                                              100                                                                              100                                                                              100 100 100 100 100                                 Barnyardgrass                                                                            100                                                                              100                                                                              100                                                                              100                                                                              100                                                                              90  100 95  80  100                                 Green Foxtail                                                                            100                                                                              100                                                                              100                                                                              100                                                                              100                                                                              95  100 100 80  100                                 Johnsongrass                                                                             100                                                                               90                                                                              100                                                                               80                                                                               90                                                                              50  100 80  30  80                                  Yellow Nutsedge                                                                          100                                                                               50                                                                              100                                                                               40                                                                               90                                                                              80  --  --  --  --                                  __________________________________________________________________________     *The compound number is the number of the Example in which the particular     compound was prepared.                                                   

For herbicidal application, the active compounds as defined areformulated into herbicidal compositions by admixture in herbicidallyeffective amounts with adjuvants and carriers normally employed in theart for facilitating the dispersion of active ingredients for theparticular utility desired, recognizing the fact that the formulationand mode of application of a toxicant may affect the activity of thematerial in a given application. Thus, for agricultural use the presentherbicidal compounds may be formulated as granules of relatively largeparticle size, water-soluble or water-dispersible granules, as powderydusts, as wettable powders, emulsifiable concentrates, as solutions oras any of several other known types of formulations, depending on thedesired mode of application.

For preemergence application these herbicidal compositions are usuallyapplied either as sprays, dusts, or granules to the areas in whichsuppression of vegetation is desired. For postemergence control ofestablished plant growth, sprays or dusts are most commonly used. Theseformulations may contain as little as 0.5% to as much as 95% or more byweight of active ingredient.

Dusts are free flowing admixtures of the active ingredient with finelydivided solids such as talc, natural clays, kieselguhr, flours such aswalnut shell and cottonseed flours, and other organic an inorganicsolids which act as dispersants and carriers for the toxicant; thesefinely divided solids have an average particle size of less than about50 microns. A typical dust formulation useful herein is one containing1.0 part of the herbicidal compound and 99.0 parts of talc.

Wettable powders, also useful formulations for both pre- andpostemergence herbicides, are in the form of finely divided particleswhich disperse readily in water or other dispersant. The wettable powderis ultimately applied to the soil either as a dry dust or as an emulsionin water or other liquid. Typical carriers for wettable powders includeFuller's earth, kaolin clays, silicas, and other highly absorbent,readily wet inorganic diluents. Wettable powders normally are preparedto contain about 5-80% of active ingredient, depending on the absorbencyof the carrier, and usually also contain a small amount of a wetting,dispersing or emulsifying agent to facilitate dispersion. For example, auseful wettable powder formulation contains 80.8 parts of the herbicidalcompound, 17.9 parts of Palmetto clay, and 1.0 part of sodiumlignosulfonate and 0.3 part of sulfonated aliphatic polyester as wettingagents. Frequently, additional wetting agent and/or oil will be added tothe tank-mix for postemergence application to facilitate dispersion onthe foliage and absorption by the plant.

Other useful formulations for herbicidal applications are emulsifiableconcentrates. Emulsifiable concentrates are homogeneous liquid or pastecompositions dispersible in water or other dispersant, and may consistentirely of the herbicidal compound and a liquid or solid emulsifyingagent, or may also contain a liquid carrier, such as xylene, heavyaromatic naphthas, isophorone, or other non-volatile organic solvent.For herbicidal application these concentrates are dispersed in water orother liquid carrier, and normally applied as a spray to the area to betreated. The percentage by weight of the essential active ingredient mayvary according to the manner in which the composition is to be applied,but in general comprises 0.5 to 95% of active ingredient by weight ofthe herbicidal composition.

Typical wetting, dispersing or emulsifying agents used in agriculturalformulations include, for example, the alkyl and alkylaryl sulfonatesand sulfates and their sodium salts; polyhydric alcohols; and othertypes of surface active agents, many of which are available in commerce.The surface active agent, when used, normally comprises 1% to 15% byweight of the herbicidal composition.

Other useful formulations for herbicidal applications include simplesolutions of the active ingredient in a dispersant in which it iscompletely soluble at the desired concentration, such as acetone,alkylated naphthalenes, xylene or other organic solvents. Granularformulations, wherein the toxicant is carried on relatively coarseparticles, are of particular utility for aerial distribution or forpenetration of cover crop canopy. Pressurized sprays, typically aerosolswherein the active ingredient is dispersed in finely divided form as aresult of vaporization of a low boiling dispersant solvent carrier, suchas the Freons, may also be used. Water-soluble or water-dispersablegranules are also useful formulations for herbicidal application of thepresent compounds. Such granular formulations are free-flowing,non-dusty, and readily water-soluble or or water-soluble orwater-miscible. These soluble or dispersible granular formulationsdescribed in U.S. Pat. No. 3,920,442, incorporated herein by referenceas useful herein with the present herbicidal compounds.

The active herbicidal compounds of this invention may be formulatedand/or applied with insecticides, fungicides, nematicides, plant growthregulators, fertilizers, or other agricultural chemicals and may be usedas effective soil sterilants as well as selective herbicides inagriculture. In applying an active compound of this invention, whetherformulated alone or with other agricultural chemicals, an effectiveamount and concentration of the active compound is of course employed.

The active herbicidal compounds of this invention may be used incombination with other herbicides, e.g. they may be mixed with, say, anequal or larger amount of a known herbicide such as chloroacetanilideherbicides such as2-chloro-N-(2,6-diethylphenyl)-N-(methoxymethyl)acetamide (alachlor),2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl)acetamide(metalachlor), and N-chloroacetyl-N-(2,6-diethylphenyl)glycine(diethatyl-ethyl); benzothiadiazinone herbicides such as3-(1-methylethyl)-(1H)-2,1,3-benzothiadiazine-4-(3H)-one-2,2-dioxide(bentazon); triazine herbicides such as6-chloro-N-ethyl-N-(1-methylethyl)-1,3,5-triazine-2,4-diamine(atrazine), and2-4-chloro-6-(ethylamino)-1,3,5-triazin-2-ylamino-2-methylpropanenitrile(cyanazine); dinitrolaniline herbicides such as2,6-dinitro-N,N-dipropyl-4-(trifluoromethyl)benzeneamine (trifluralin);and aryl urea herbicides such asN'-(3,4-dichlorophenyl)-N,N-dimethylurea (diuron) andN,N-dimethyl-N'-3-(trifluoromethyl)phenylurea (fluometuron).

It is apparent that various modifications may be made in the formulationand application of the novel compounds of this invention, withoutdeparting from the inventive concepts herein, as defined in thefollowing claims.

We claim:
 1. The compound of the formula ##STR11##
 2. An herbicidalcomposition comprising an herbicidally effective amount of the compoundof claim 1 in admixture with a suitable carrier.
 3. A method forcontrolling undesired plant growth which comprises applying to the locuswhere control is desired an herbicidally effective amount of thecomposition of claim
 2. 4. The method of claim 3 in which thecomposition is applied preemergently to the locus where control isdesired and said locus is planted or to be planted with cotton.